In resent years, for meeting the requirements of developing electronic equipment, especially communication equipments such as mobilephone, a thinner battery used as one of the necessary components of the said equipments is required. The conventional metal case used as the sealing case of the battery core is thicker and occupies more space. In order to overcome the above-mentioned defects, a composite material of metal foil and plastic film or thermos-fused polymer film is adopted. However, the strength of this composite material is not sufficient, and it is easier to deform which is harmful to the electronic equipments. Therefore, the application field of this composite material is limited It is well-known in the art that, during the use of some common batteries with a liquid electrolyte, such as nickel-cadmium battery, metal hydride-nickel battery, lithium ion battery and lithium battery, especially under the overcharged state, the production of gases is unavoidable. In view of safety, it is necessary to select a battery case having better mechanical strength. In consideration of safety, the metal case undoubtedly is a good choice. However, the thinness of the metal case is bound to bring many difficulties in manufacture process, including welding and sealing. For examples, the trough body of the battery is usually deeper which makes it difficult to put the battery core into the trough or the active substance on the electrode will be scraped during the process of putting the battery core into the trough. Moreover, the smaller area of the cover of the battery also increases the difficulty of laser welding. Moreover, the explosion-protective device mounted in the trough of the battery is usually a thin whittling concave trough. Because of the nature of metal and poor uniformity of thickness after whittling, the explosion-protective performance of the battery is generally unsatisfying. Having conducted studies for a long time, the inventors of the present invention eventually improved the battery case and the terminal sealing system to overcome the above-mentioned defects successfully, thereby completes the present invention.